U.S. President Donald Trump said on Monday he does not mind if Microsoft Corp. buys the Chinese-owned short-video app TikTok, but any purchase by an American company would have to be done by a Sept. 15 deadline.

The Republican president, who last week threatened to ban TikTok over national security concerns, said he had a great conversation with Microsoft's chief executive and that it might be easier if the company buys all of TikTok rather than 30 per cent.

Trump's comments confirmed a Reuters report Sunday that he had agreed to give China's ByteDance 45 days to negotiate a sale of TikTok to Microsoft.

Trump also said the U.S. Treasury would need to get a lot of money out of a TikTok deal, but it's not clear how that would happen.

Microsoft said Sunday that CEO Satya Nadella had spoken to Trump and "is prepared to continue discussions to explore a purchase of TikTok in the United States."